Complex tissue: Complex tissues are made of more than one type of cells. All these cells
coordinate to perform a common function.
There are two types of complex tissues- Xylem and Phloem.
They are both conducting tissues and constitute a vascular bundle.
Xylem: Xylem is a complex vescular tissue which is in all parts such as root, stem and leaf of the plant. It is composed of several types of cells. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres.
The cells of this tissue have thick walls and many of them are non-living.
(i) Tracheids: These are long elongated tubular cells. Tracheids cells are dead. They are found in all vascular plants. Its main function is conduction of water and minerals from root to stem.
(ii) Vessels: These are pipe-like structure. Vessels are dead and have lignified cell wall. They also participate conduction of water and minerals.
(iii) Xylem parenchyma: These are simple parenchyma found in the xylem. These are living cells which store food material.
(iv) Xylem fibres: These are dead cells which provide mechanical support to the plant.
Phloem: Phloem is a conducting or vascular tissue of the plants. Phloem is made up of four types of elements: sieve tubes, companion cells, phloem fibres and phloem parenchyma.
and the phloem parenchyma.
(i) Sieve tubes: These are tubular cells with perforated walls. These cells are responsible for transportation of food and nutrients.
(ii) Companion cells: These cells are found associated with sieve tubes and connected with it by simple pits. These cells are long, narrow and thin walled. These cells are living.
(iii) Phloem fibres: They have thick cell wall and they provide mechanical support to plant.
(iv) Pholem parenchyma: These cells are living and often cylindrical in shape.
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